Your own if/else

[Marcin Raczkowski]

Hello i remeber someone asking fif it's possible in Ruby - and i have no
idea if it was replyied, anyway i wanted to share my idea how to make
your own if/else/elsif

class Object
def else
self
end

def elsif(condition,&block)
self
end

def if(condition,&block)
(!condition && Else) || (condition && block.call)
end
end

class Else
def self.else(&block)
block.call
end

def self.elsif(condition, &block)
self.if(condition, &block)
end
end



and now we can do:

irb(main):024:0> self.if(true){:true}.else{:false}
=> :true
irb(main):025:0> self.if(false){:true}.else{:false}
=> :false
irb(main):051:0> self.if(false){:true}.elsif(true){:true}.else{nil}
=> :true
irb(main):052:0> self.if(false){:true}.elsif(false){:true}.else{nil}
=> nil
irb(main):053:0> self.if(true){k}.elsif(true){:not_ok}.else{:not_ok}
=> k
irb(main):056:0> self.if(false){:not_ok}.elsif(true){k}.else{:not_ok}
=> k


this aproach is elegant becouse even if object have method else or elif
or even if declared then it'll bahave as expected !!!
Also i didn't use any of old if/else statements, i didn't even use tri
argument operator (cond ? true : false), it's all implemented using
boolean logic!!

Ok, now probably comes question - what we can do with it - of course -
create less boolean logic!!!

module Fuzzy
def self.if(float, &block)
condition = rand <= float
(!condition && Else) || (condition && block.call)
end
end

now we provide if function with float between 0 and 1 - which represents
probability of achieveing goal

Fuzzy.if(0.99){puts "pretty standard stuff"}.else{puts "**** man, you
really have luck"}

with some luck (3th try for me) you can get something like this:
irb(main):097:0> 10.times{ Fuzzy.if(0.99){puts "pretty standard
stuff"}.else{puts "**** man, you really have luck"} }
pretty standard stuff
pretty standard stuff
pretty standard stuff
pretty standard stuff
**** man, you really have luck
pretty standard stuff
pretty standard stuff
pretty standard stuff
pretty standard stuff
pretty standard stuff
=> 10

What else - of course this way you can do random mutations in genetic
algorithms, of course there's other ways to achieve that - but this one
is fun

currently there's only one problem with this:

irb(main):099:0> self.if(false){:not_ok}
=> Else
while normally you get nil, also Else evaluates to >true< in
expressions, i thought about using Nil or False class instead of else -
but then block returning nil or false would trigger else block too.
so there's tradeoff. Also Else class could cause name conficts so
someone can rename it to
WierdClassThatServesOnlyAsMetaProgramingMagickElse to avoid it


------------

And last thing - i tried hacking ruby interpreter to treat >if< not as
keyword - but as Kernel method - but not much luck yet,


have phun with Ruby

 

[Trans]

Hello i remeber someone asking fif it's possible in Ruby - and i have no
idea if it was replyied, anyway i wanted to share my idea how to make
your own if/else/elsif

class Object
def else
self
end

def elsif(condition,&block)
self
end

def if(condition,&block)
(!condition && Else) || (condition && block.call)
end
end

class Else
def self.else(&block)
block.call
end

def self.elsif(condition, &block)
self.if(condition, &block)
end
end

and now we can do:

irb(main):024:0> self.if(true){:true}.else{:false}
=> :true
irb(main):025:0> self.if(false){:true}.else{:false}
=> :false
irb(main):051:0> self.if(false){:true}.elsif(true){:true}.else{nil}
=> :true
irb(main):052:0> self.if(false){:true}.elsif(false){:true}.else{nil}
=> nil
irb(main):053:0> self.if(true){k}.elsif(true){:not_ok}.else{:not_ok}
=> k
irb(main):056:0> self.if(false){:not_ok}.elsif(true){k}.else{:not_ok}
=> k

this aproach is elegant becouse even if object have method else or elif
or even if declared then it'll bahave as expected !!!
Also i didn't use any of old if/else statements, i didn't even use tri
argument operator (cond ? true : false), it's all implemented using
boolean logic!!

Ok, now probably comes question - what we can do with it - of course -
create less boolean logic!!!

module Fuzzy
def self.if(float, &block)
condition = rand <= float
(!condition && Else) || (condition && block.call)
end
end

now we provide if function with float between 0 and 1 - which represents
probability of achieveing goal

Fuzzy.if(0.99){puts "pretty standard stuff"}.else{puts "**** man, you
really have luck"}

with some luck (3th try for me) you can get something like this:
irb(main):097:0> 10.times{ Fuzzy.if(0.99){puts "pretty standard
stuff"}.else{puts "**** man, you really have luck"} }
pretty standard stuff
pretty standard stuff
pretty standard stuff
pretty standard stuff
**** man, you really have luck
pretty standard stuff
pretty standard stuff
pretty standard stuff
pretty standard stuff
pretty standard stuff
=> 10

What else - of course this way you can do random mutations in genetic
algorithms, of course there's other ways to achieve that - but this one
is fun

currently there's only one problem with this:

irb(main):099:0> self.if(false){:not_ok}
=> Else

I bet you could fix that with lazy evaluation.

T.

 

[Marcin Raczkowski]

I bet you could fix that with lazy evaluation.

T.

Fix what? and how exactly?

 

[Curt Sampson]

Actually, I find the Smalltalk way a little more elegant. The booleans
have true:, false:, and true:false: methods; each of the parameters
takes a block:

x > 3 true: [ 1 + 1 ] false [ 0 ]

(If I recall correctly.)

cjs

 

[Marcin Raczkowski]

Actually, I find the Smalltalk way a little more elegant. The booleans
have true:, false:, and true:false: methods; each of the parameters
takes a block:

x > 3 true: [ 1 + 1 ] false [ 0 ]

(If I recall correctly.)

cjs

Well you can do it with ruby (and even c)like this:

x >3 ? [1+2] : [0]


Inyaway i just wanted to make someone's life little easier, and/or more
fun

 

[Rick DeNatale]

Actually, I find the Smalltalk way a little more elegant. The booleans
have true:, false:, and true:false: methods; each of the parameters
takes a block:

x > 3 true: [ 1 + 1 ] false [ 0 ]

(If I recall correctly.)

x > 3 ifTrue:[1 + 1] ifFalse:[0]

However, most Smalltalk implementations cheat and the compiler turns
this into test and branch bytecodes rather than sending the
ifTrue:ifFalse: message